Thanks, Andrew. It's encouraging to think of snails having more than rudimentary vision. I had only come across one webpage on this http://www.applesnail.net/content/anatomy/senses.php -- admittedly not a terrestrial snail example, but with reasonably recent references.

Wouldn't the visual discrimination of a snail depend to a large extent on its nervous system outside the eyes themselves? Maybe there have been some experiments with snail neurons.

Say, where's Aydin? He might have some experience with landsnails doing behaviors that seem odd to humans.

David Kirsh
Durham, NC

-----Original Message-----
>From: Andrew Grebneff <[log in to unmask]>
>Sent: Aug 27, 2009 6:58 PM
>To: [log in to unmask]
>Subject: Re: [CONCH-L] further adventures of Eli and Milton
>
>> For a few seconds, their eyestalks intertwined, i.e. doubled back nearly 180 degrees around each the other's like intertwined pinkies. They then traveled separately but parallel for a while.
>
>Cute... they're in love!
>
>> Also, is there any simulation of what snails "see",  just as there are simulations of what flies' compound eyes "see"?
>
>The old "mosaic image" idea is long dead. Arthropod compound eyesight
>is excellent; each cell in the eye produces an image which overlaps
>those of its neighbors, producing a flawless image... almost
>wraparound in the case of eg dragonflies.
>
>I'd bet that the majority of snails have pretty good vision. It would
>certainly be to their advantage. Their eyes are typically complex, and
>even a pinhole camera (and therefore a lensless eye such as that of
>nautilus) can give a decent image.
>
>--
>Regards
>Andrew Grebneff
>Dunedin, New Zealand
>Fossil preparator
>Mollusc, Toyota & VW van fanatic
>
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